Introduction
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SPNU563A–March 2018
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Enhanced Capture (eCAP) Module
33.1 Introduction
Uses for eCAP include:
• Speed measurements of rotating machinery (for example, toothed sprockets sensed via Hall sensors)
• Elapsed time measurements between position sensor pulses
• Period and duty cycle measurements of pulse train signals
• Decoding current or voltage amplitude derived from duty cycle encoded current/voltage sensors
33.1.1 Features
The eCAP module includes the following features:
• 4-event time-stamp registers (each 32 bits)
• Edge polarity selection for up to four sequenced time-stamp capture events
• Interrupt on either of the four events
• Single shot capture of up to four event time-stamps
• Continuous mode capture of time-stamps in a four-deep circular buffer
• Absolute time-stamp capture
• Difference (Delta) mode time-stamp capture
• All above resources dedicated to a single input pin
• When not used in capture mode, the ECAP module can be configured as a single channel PWM output
33.1.2 Description
One eCAP channel has the following independent key resources:
• Dedicated input capture pin
• 32-bit time base (counter)
• 4 x 32-bit time-stamp capture registers (CAP1-CAP4)
• 4-stage sequencer (Modulo4 counter) that is synchronized to external events, ECAP pin rising/falling
edges.
• Independent edge polarity (rising/falling edge) selection for all 4 events
• Input capture signal prescaling (from 2 to 62)
• One-shot compare register (2 bits) to freeze captures after 1 to 4 time-stamp events
• Control for continuous time-stamp captures using a 4-deep circular buffer (CAP1-CAP4) scheme
• Interrupt capabilities on any of the 4 capture events
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